What every compiler writer should know about programmers (2015) [pdf]

Post by AlotOfReading » Tue, Feb 17, 2026, 5:47 AM UTC

WalterBright wrote: post #8

Joker_vD wrote: post #5

In the end it all boils to a very simple argument. The C programmers want the C compilers to behave one way, the C implementers want the C compilers to behave the other way. Since the power structure is what it is — the C implementers are the ones who write the C standard and are the ones who actually get to implement the C compilers — the C compilers do, and will, behave the way the C implementers want them to. In t…

> behave the way the C implementers want them to If you don't please your users, you won't have any users.

Post by AlotOfReading » Tue, Feb 17, 2026, 5:54 AM UTC

Joker_vD wrote: post #4

zephen wrote: post #3

Here's a cogent argument that any decision by compiler writers that they can do whatever they wish whenever they encounter an "undefined behavior" construct is rubbish: https://www.yodaiken.com/2021/05/19/undefined-behavior-in-c-... And here's a cautionary tale of how a compiler writer doing whatever they wish once they encounter undefined behavior makes debugging intractable: https://www.quora.com/What-is-the-most-s…

Wow, that's a very torturous reading of a specific line in a standard. And it doesn't really matter what Yodaiken thinks this line means because standard is written by C implementers for (mostly) C implementers. So if C compile writers think this line means they can use UB for optimizing purposes, then that's what it means. Yeah, I know it breaks the common illusion among the C programmers that they're "close to the…

Post by catlifeonmars » Tue, Feb 17, 2026, 6:02 AM UTC

BeeOnRope wrote: post #14

rurban wrote: post #12

This was 2015, and we still have no -Wdeadcode, warning of removal of "dead code", ie what compilers think of dead code. If a program writer writes code, it is never dead. It is written. It had purpose. If the compiler thinks this is wrong, it needs to warn about it. The only dead code is generated code by macros.

Dead code is extremely common in C or C++ after inlining, other optimizations.

Post by dotancohen » Tue, Feb 17, 2026, 6:05 AM UTC

seg_lol wrote: post #6

Joker_vD wrote: post #5

In the end it all boils to a very simple argument. The C programmers want the C compilers to behave one way, the C implementers want the C compilers to behave the other way. Since the power structure is what it is — the C implementers are the ones who write the C standard and are the ones who actually get to implement the C compilers — the C compilers do, and will, behave the way the C implementers want them to. In t…

How about we agree on the ABI and everyone can have their own C compiler. Everyone C's the world through their own lenses.

Post by deathanatos » Tue, Feb 17, 2026, 6:11 AM UTC

zephen wrote: post #3

Here's a cogent argument that any decision by compiler writers that they can do whatever they wish whenever they encounter an "undefined behavior" construct is rubbish: https://www.yodaiken.com/2021/05/19/undefined-behavior-in-c-... And here's a cautionary tale of how a compiler writer doing whatever they wish once they encounter undefined behavior makes debugging intractable: https://www.quora.com/What-is-the-most-s…

  code.cpp:4:6: runtime error: execution reached the end of a value-returning function without returning a value